Oxygen-rich Supernova Remnant Research Articles

Models for the Emission Line Spectra of Oxygen-rich Supernova Remnants

The mechanism of excitation of the oxygen-rich class of young supernova remnants (SNRs), typified by the fast-moving knots of Cas A, is not currently understood. In this paper we review the available optical data and the current state of attempts at theoretical modelling. A new model is proposed which dramatically improves the fit of the theory with the observations for this class of SNRs. The model is of an X-ray driven R-type ionisation front precursor of a very fast shock. The peculiarities of the thermal balance in oxygen allow an enormous amount of superheating in the gas, which is first exposed to the X-ray ionising field, and the optical emission occurs in this superheated gas. The fit with observation is sufficiently good to give some degree of confidence that the mode of excitation of the plasma has at last been identified, and elemental abundances in four young oxygen-rich SNRs are derived.

SN 1985f - Death of a Wolf-Rayet star

The optical spectrum of SN 1985f has been analyzed, and the supernova ejecta is shown to contain approximately 5 or more solar masses of oxygen and very little hydrogen. It is suggested that the explosion resulted from the pair instability supernova of a WO Wolf-Rayet star of about 50 solar masses, and that the optical luminosity of the supernova is powered by the radioactive decay of Co-56 synthesized in the explosion. As calculated from the rate of the optical emission decay, the explosion occurred about 350 days before its discovery in February, 1985. It is believed that some of the oxygen-rich supernova remnants may also have been produced by explosions of WO stars.

Ultraviolet observations of the peculiar supernova remnant in NGC 4449

IUE spectra were obtained of the emission region in the irregular galaxy NGC 4449 that has been identified as a young, oxygen-rich supernova remnant embedded in an H II region. The spectra show a blue continuum with a strong C IV 1550 P Cygni feature. Comparison to spectral standard stars observed with IUE shows similarities to O3-O7 V and early B Ia stars, indicating that massive young stars are present in the H II region. This comparison also indicates that the ultraviolet extinction in NGC 4449 may be peculiar. Careful inspection of the line-by-line data reveals a broad emission feature at 1657 A that may be semiforbidden O III emission from the supernova remnant. These observations are used in conjunction with shock model calculations to estimate limits on the relative abundances of carbon, silicon, and oxygen in the supernova remnant.

Ring ejection in type II supernovae - IE 0102.2-7219 in the small magellanic cloud

view Abstract Citations (64) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ring ejection in type II supernovae : 1E 0102.2-7219 in the Small Magellanic Cloud. Tuohy, I. R. ; Dopita, M. A. Abstract A velocity map is presented of the young oxygen-rich supernova remnant (IE 0102.2-7219) in the Small Magellanic Cloud, obtained with the Anglo-Australian Telescope. The velocity structure is complex and implies a high degree of asymmetry during the type II supernova explosion. Our velocity data can be modeled in terms of a severely distorted ring of ejecta. This result, together with the evidence for expanding rings in similar remnants, suggests nonspherical ejection to be an intrinsic characteristic of type II supernova. Two-dimensional spectroscopy of the diffuse halo of emission which partially surrounds IE 0102.2-7219 has also been obtained. The halo emits in the He II 4686 wavelength line and is either a fossil H II region created by a UV flash accompanying the supernova, or alternatively is being excited by intense UV radiation from the remnant itself. It is the first clear association of a high-excitation region with a supernova remnant. Publication: The Astrophysical Journal Pub Date: May 1983 DOI: 10.1086/184020 Bibcode: 1983ApJ...268L..11T Keywords: Astronomical Maps; Magellanic Clouds; Stellar Mass Ejection; Supernovae; Velocity Distribution; H Ii Regions; Helium; Line Spectra; Oxygen; Supernova Remnants; Ultraviolet Spectra; X Ray Sources; Astrophysics full text sources ADS | data products SIMBAD (1) NED (1)

A Dynamical Study of the Young Oxygen-Rich Supernova Remnant in the Small Magellanic Cloud

We present a velocity map of the young oxygen-rich supernova remnant (1E0102.2–7219) in the Small Magellanic Cloud, obtained with the Anglo-Australian Telescope. The velocity structure is complex, and implies a high degree of asymmetry during the Type II supernova explosion. Our data can be modelled geometrically in terms of a severely distorted ring of oxygen-rich ejecta. This result, together with the evidence for expanding rings in similar remnants, suggests non-spherical ejection to be an intrinsic characteristic of Type II supernovae. We have also obtained two-dimensional spectroscopy of the diffuse halo of emission which partially surrounds 1E0102.2–7219. The halo exhibits the high excitation line of HeII λ4686, and is either a fossil HII region created by a UV flash accompanying the supernova, or alternately, is being excited by intense UV radiation from the remnant itself. It is the first clear association of a high excitation region with a supernova remnant.

A new oxygen-rich supernova remnant in the Large Magellanic Cloud

view Abstract Citations (74) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A new oxygen-rich supernova remnant in the Large Magellanic Cloud Mathewson, D. S. ; Dopita, M. A. ; Tuohy, I. R. ; Ford, V. L. Abstract The identification of the LMC radio/X-ray object 0540-69.3 with an optical nebulosity associated with a supernova remnant is reported. The optical component was found in a search conducted with the 3.9-m Anglo-Australian Telescope in the direct imaging mode in H beta, the forbidden O III line at 5007 A, the forbidden N II line at 6584 A and the continuum at 5323 A. An intense circular source of forbidden O III emission was discovered, along with a larger weaker arc of forbidden O III which together surround the radio source. No H beta emission was detected; however, a faint annulus coincident with the intense oxygen feature was found in forbidden N II. Spectroscopic analysis of the O III features indicates the annulus to have a velocity dispersion around 3000 km/sec, characteristic of a very young supernova remnant, while the arc is most likely background emission from the photoionized nebula. Publication: The Astrophysical Journal Pub Date: December 1980 DOI: 10.1086/183406 Bibcode: 1980ApJ...242L..73M Keywords: Magellanic Clouds; Optical Emission Spectroscopy; Oxygen Spectra; Radio Sources (Astronomy); Supernova Remnants; X Ray Sources; Astronomical Spectroscopy; Forbidden Transitions; Nebulae; Radio Astronomy; Radio Telescopes; Spectrometers; Astronomy full text sources ADS |